NEW YORK (AP) — Monster Beverage is hitting back at a lawsuit alleging its energy drinks were responsible for the death of a 14-year-old girl, saying that no blood test was performed to confirm that the girl died of "caffeine toxicity."

The disclosures come amid intensifying scrutiny of energy drinks and their caffeine levels. A lawsuit filed last year by the family of Anais Fournier said the girl went into cardiac arrest after drinking two, 24-ounce (680-gram) cans of Monster drinks in a 24-hour period. The Food and Drug Administration has also said it is investigating reports of deaths linked to energy drinks, including five that cite Monster beverages. The agency notes that the reports don't prove the drinks caused the deaths.

In an interview, Monster's lawyer Daniel Callahan said the company hired a team of physicians to review medical records, which he said suggest Anais Fournier died of natural causes brought on by her pre-existing heart conditions. The team found no medical evidence for an autopsy report that said "caffeine toxicity" was a factor, he said.

Callahan said that finding was made based on interviews with Anais Fournier's mother, who told the medical examiner's office the girl had consumed energy drinks before her death.

A spokesman for Maryland's chief medical examiner could not immediately confirm whether a blood test had been performed to check for caffeine levels. He noted the cause of death was "cardiac arrhythmia due to caffeine toxicity complicating mitral valve regurgitation in the setting of Ehler's-Danlos syndrome," which is a heart condition.

A lawyer for the Fournier family did not immediately have a comment on Monster's disclosures.

The company also said that evidence obtained as part of the lawsuit's discovery process shows Anais Fournier regularly drank coffee and energy drinks without incident. Callahan also noted that none of the other incidents the FDA is investigating has resulted in a lawsuit against Monster.

Before the spate of bad publicity that dragged down its stock price in recent months, Monster had been enjoying enormous growth because of the surging popularity of energy drinks. In 2011, sales volume for energy drink overall rose 17%, according to the industry tracker Beverage Digest, with the three biggest players — Monster, Red Bull and Rockstar — all logging double-digit gains.

But the success has also brought greater scrutiny. This summer, the New York state attorney general's office subpoenaed Monster as part of an investigation into how energy drinks are made and marketed. Subpoenas were also sent to Living Essentials, which makes 5-Hour Energy shots, and PepsiCo Inc., which makes AMP.

Lawmakers have also called on the FDA to investigate the use of ingredients such as taurine in energy drinks and whether the caffeine levels are safe for children.

Monster has stood by the safety of its drinks, which it says contain 240 milligrams of caffeine for a 24-ounce can, compared with 330 milligrams in a 16-ounce (453.5-gram) cup of Starbucks coffee. Monster, based in Corona, California, has recently said it will begin disclosing the caffeine levels in its drink labels.